Help on procedure. Distance between centers of arcs compared to a fixed center.

[[Lu...]]

Hello!

I'm using my T-SCAN HAWK 2 scanner.

I have the need to check the concentricity of a fixed center just in Z AXIS (HEIGHT) with many pieces that have an arc like shown here: I would appreacite some guidance on the procedure of what have I done as a try so later I can do it correctly.

Specially on the alignment and how to obtain the difference of heights between the axis.

My idea is to scan ( by parts, because the machine is huge and the photogrammetry works up to 4 meters) the C0 and C0.1 to get the distance between centers and use the mas reference to compare them with C1, C2, C3, C4, etc up to C20. And when I have no more distance due to the range, compare between the arcs, for example C15 to C16, C17, C18...

I just did a try on 3 arcs, C1, C2 and C3 as shown.

 

For the alignment, I would like to have one arc center as the X axis , but then how could I define the Z axis so i have the height distance between them?? I tried a 3-2-1 but still have some deviation

 

And after this, Should I just construct cylinders in each arc and then construct a 2 line distance between cylinders and the fixed one and Check the Z distance?

 

 

[[Ti...]]

I'm just commenting to say you are not checking concentricity if you are checking the z-height only, you are checking z-height position. There is no way you can check concentricity with this method. Concentricity is a measurement of many opposing diametrically opposed mid points that must remain in a cylindrical zone to a primary datum axis. This is such a problem they removed it from the most recent ASME standard in 2018. The alternative is runout, but it is possible for runout to fail when concentricity would pass....think about an octagon...if you check the runout on an octagon with a test indicator it would fail terribly, but if you plot the opposing mid-points of an octagon it would pass a concentricity check.   Concentricity is not the surface check, but the mid point plot of the surfaces check, where runout is the actual real surface check....that is why is is now preferred. Concentricity is a balance check...ie if you high spin an octagon it will spin balanced, but fail a runout check and a profile check.

If size is not an issue you can use surface profile to replace both the above, but profile is going to facture in size. Profile is checking concentricity as well as size. There is a new modifier in the standard called the dynamic modifier that checks profile without regard to size but I don't see it in the Zeiss software as of my version.

 

Zeiss, is the dynamic profile modifier available yet?

 

 

 

 

 

Edited 20 hours ago

[[Lu...]]

Thanks for your reply Tim! That's right, my mistake. I just need the comparisson between z-height position! I asked to a Zeiss member and told me if I was doing good, but still need a better surface to set my coordenate system!

I will post my progress soon!

 

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[[Ja...]]

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 you also have a rather not fun partial arc problem.

Attempting to calculate cylinders with such little arc is going to lead to unstable results.

As a possible resolution to what i think you are after....create the cylinder on C0 , then you can create a surface devaiation of each of the arcs to that fitted primative. You may also be able to set this calculation to a given direction but im not sure this visualisation would help much .

Other possible solution...take a section through the arc by say a mid plane by the two sides, create a touch point edge that contacts the underside of the arc , describing the lowest point of the arc, create a projected distance from this point to the centre axis of the C0 primative